Most wines are aged in French oak or American oak, but some other woods can be specified for certain types of wine. There is a tannin flavour which is imparted by wood phenolics to the wine and this is traditionally acceptable, and consequently there is a requirement for large quantities of the appropriate timber. If casks are to be made by the usual cooperage methods, then not only is there an extensive use of available time but also the usage of timber is excessive and therefore a cask made with staves of French or American oak by traditional cooperage methods is excessively expensive.